public class Test {
    public static void main(String[] args) {
        Student student = new Student("小a", 18, "高中");
        System.out.println(student);
        Student s1 = new Graduate("小b", 19, "研究生", "数据库分析");
        System.out.println(s1);
        Student s2 = new Undergraduate("小c", 20, "本科生", "计算机科学与技术");
        System.out.println(s2);
    }
}
